Yet it appears unlikely that he will be at Dortmund for much longer. He has long-since revealed that he will not be extending his contract with the Bundesliga side, which expires in 2014, and, while Dortmund suggest otherwise, a departure this summer is widely expected.

Both Manchester United and Bayern Munich have been strongly linked to the 24-year-old, although the Telegraph reports that Chelsea and Arsenal have also been keeping tabs on the player.

It is thought, however, that while Lewandowski would welcome a move to the Premier League, Manchester United is his preferred destination.

The Poland international’s agent has also now claimed that a deal has already been reached with an unnamed club.

"We are in agreement with a club and have the right to change this summer,” Maik Barthel told Sport Bild. “All the claims of Dortmund are met."

Chelsea’s first signing of the summer looks set to be another forward currently plying his trade in Germany -- Bayer Leverkusen’s Andre Schurrle.

The Blues tried to sign the Germany international last summer, but had a bid rejected by the Bundesliga side. There have been increasing reports in recent weeks, though, that Chelsea are back in talks over a proposed £20 million move. And Leverkusen’s director of sport Rudi Voller has now confirmed the stories.

“I am waiting for information from either Leverkusen or Chelsea, but there could be some positive news by the end of this weekend,” Ingo Haspel revealed, according to the Daily Mail. “It is an indication of how much Chelsea want the player that they are continuing to negotiate.”

The Daily Mail believes that as part of the deal, Chelsea winger Kevin de Bruyne will be heading to Leverkusen on loan. The young Belgian midfielder has yet to make a competitive appearance for the Blues since signing from Genk in January 2012. He has impressed on a season-long loan with Werder Bremen this campaign.

Less likely to come to fruition is speculation of Chelsea’s interest in Alexis Sanchez. Citing stories in Spain, the Daily Express reports that the Blues have are keen to bring the Chile international to Stamford Bridge.

Sanchez, 24, has struggled to fulfill expectations at Barcelona since his big-money move from Udinese in the summer of 2011. The forward has also been linked to Premier League sides Manchester United and Arsenal.